The mechanism of human chorionic gonadotropin (hCG) synthesis, and the stimulation of hCG synthesis by actinomycin D (Act D) will be investigated in human malignant trophoblast cultures. Radioimmune precipitation techniques will be developed for the isolation of hCG. Cellular hCG and secreted hCG will be studied in terms of recognition by anti-hCG antiserums. The effect of Act D on RNA synthesis in the trophoblast will be examined. The role of microtubules and calcium in the secretory process will be evaluated. Studies on the effect of hCG on lymphocyte blastogenic response to mitogens will be extended. BIBLIOGRAPHIC REFERENCES: Pattillo, R.A., and Hussa, R.O. Early stimulation of human chorionic gonadotropin secretion by dibutyryl cyclic AMP and theophylline in human malignant trophoblast cells in vitro: inhibition by actinomycin D, gamma-amanitin, and cordycepin. Gynecol. Invest., In Press, 1976. Pattillo, R.A., Shalaby, M.R., Hussa, R.O. and Mattingly, R.F. In vitro effect of crude and purified HCG on blastogenesis in lymphocytes. Obstet. Gynecol., In Press, 1976.